Process of forming high-percentage tungsten alloys.



about aluminothermic reactions and be fused with diflicult UNITED STATES PATENT OFFICE.

HANS eomscnmr AND OTTOWEIL, 0F ESSEN-ON-THE-RUHR, GERMANY, ASSIGNORS TO GOLDSCHKIDT THEBMI'I COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

P300188 01' FORMING HIGH-PERCENTAGE TUNGSTEN ALLOYS Specification of Letters ratent.

Paten'ted Aug. '7, 1917.

Be it known that we, Hans Gomsonmn'r and O'rm WmL, subjects of the King of Prussia, German Emperor, and residents of Essen-on-the-Ruhr, in the Province of the Rhine, German Empire, have jointly 1n- ,vented certain new and useful Im rovements in Processes of Forming Hig -Percentage Tungsten Alloys, of which the following is an exact specification.

Tungsten alloys'of high ercentage, which are used for various 1n ustrial purposes, more particularly ferro tungsten were hitherto'produced enerally in electric furnaces since, as is wel known, tungsten can only and only at a far higher temperature t an chromium and mol bdenum for instance. Tungsten alloys produced in electric furnaces always contain carbon so that their use for many industrial purposes is attended with disadvantages.

Attem ts have already been made to produce high-grade tungsten alloys by means of so called aluminothermic reactions by causin a mixture for instance of tungstic oxid, ferric oxid and aluminum to react. The output of metal regulus obtained in this way was however, comparatively small, because a large amount of the metal remains in the slag owing to the difficult fusibility of the tungsten.

Considering what was hitherto known their applicability to metals of high melting ppmt, it seemed justified-to assume that-a tter output of tungsten alloys of high percentage could only be obtained by addmg such .substances as raise the temperature of reaction and consequently the energy of reaction. periments have proved that a very good ield of these alloys is obtained by addingindifierent substances to the mixture for the aluminothermic reaction, for example lime or other earths or mixtures of such or similar substances, or finer-spar which in no way contribute to raising thetemperature of reaction and which do not participate in the aluminothermic reaction. In this manner high grade alloys of tungsten particularly with iron, but also with chromium, nickel, molybdenum and other metals can be produced by effecting the aluminothermic reac- Contrary to the above, ex

tion of a mixture consisting of tungstic oxid, the oxid of the metal in question, a reducing metal such as aluminum (or a mixture or allo ly of several reducing metals) and lime. he quantity of lime added may amount to about a uarter of that of the tungstic oxid'used, w ich appears very surprising andwas not to be foreseen.

Instead of adding the lime in this reaction as such it has proved advantageous to use tungstate of calcium as component of the reaction mixture. The tungstate of calcium may be produced artificially or the mineral found in natural state as scheelite (CaWVOQ may be used, after being purified 1n a suitable manner.

This aluminothermic process for obtaining tungsten alloys of high percentage can advantageously be used for incorporating tungsten or tungsten alloys of high percentage into molten metal baths, for instance ferro-tungsten. into baths of cast-iron or steel. ThlS incor oration was hitherto made either in form 0 pulverized metallic tungsten of high ercentage (up to 97%) or in the form of erro-tungsten roduced in the electric furnace and containing up t 75-85 per cent. of tungsten. This manner of introduction, however, was highly disadvantageous inasmuch 'as carbon or oxidation impurities were introduced together with the metallic-tungsten or the ferro-tungsten produced in the electric furnace; further as it was very diflicult to alloy these substances with the bath of cast-iron or steel, and. finally as one had to reckon a waste of about &6 per cent. of tungsten. All these disadvantages are avoided by adding to the bath of cast-iron or steel a mixture of ferricoxid, aluminum tungstic-oxid and, for in stance, lime (or instead of the last two substances also tungstate of calcium). The aluminothermic reaction which immediately takes place produces pure ferro-tungsten of high percentage alloying very well and almost without any waste with the cast-iron or steel, the easlly fusible slag remaining liquid on the surface of the bath. Of course the other hi h grade tungsten alloys mentioned above ormed with chromium, nickel, molybdenum and the other metals may also be introduced into molten metal baths in the same manner and with the same success as ferro-tungsten.

What we claim is: The process of formin alloys containing a high ercentage oi tungsten which I In witness whereof we have hereunto set our hands in the presence of two witnesses. 10

HANS GOLDSCHMIDT. 11.8.1 consists in e ectmg the alummothermic re- 1 5 action of a mixture comprising as a com- OTTO ponent thereof a relatively large quantity Witnesses: of flux, a tungsten compound, the oxid of CHAS. J. WRIGHT,-

the alloying metal and a reducing metal. 7 HEILEH Nmmn. 

